1. B. Schwartländer and N. Walker are in the Joint United Nations Programme on HIV/AIDS (UNAIDS), Geneva, Switzerland.
2. J. Stover, L. Bollinger, W. McGreevey, and S. Forsythe are at The Futures Group International, Washington, DC 20036, USA.
3. J. P. Gutierrez, M. Opuni, and S. Bertozzi are at the National Institute of Public Health, Cuernavaca, Mexico.
4. L. Kumaranayake and C. Watts are in the Department of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK.